Dehalogenation process



Patented May 2, 1950 Shre'wsbury N. JQ, assignors to Nopco' ChemicalCompany, Harrison, N. J ,a corporation of New Jersey Nol rawing.ApplicationF-ebruaryii; 1949 Serial No. 733486 14.'Claims'.- If

This invention relates to: a-- dehalogenation process and. moreparticularly: toa highly improved process for dehalogenating:oxidizedhalo.- genated sterol. compounds.

It has been known for a number of years that halogenated organic"compounds:- coul d be dehalogenated to produce unsaturated? organiccompounds by reactingfthe halogenated compounds with ziricin: thepresence ofla short chain organic acid such as acetic-a'cidi. Thus inU'. S;.Patent No. 1-,254,866=there is-discloseda process for producinghydrocarbon;oilssuitable. for use as drying oils'wher'ein av naturalhydrocarbon oil first chlorinated: and: then the chlorinated oil isreacted with. zinc: inthe presence" of. acetic acid in order todehalogenate thechlorinated oil, thus providing; a highly unsaturatedhydrocarbon-oil suitable for use in the paint industry.

Another example-ofthe-useof zincz'as-a dehalogenating': agent is in.the: production of purelinol'eie acid from tetrabromestea-ricacid. Sincethe various fatty acids have physical and chemical characteristicswhich. are: closely related, it is rather different to recover the.individual fatty acids inpure'form from natural fatty materials.However. linoleic acidmay be: recovered-1 in pure formby completely:saturating with halogen atoms the double-'bonds or. all the compounds ina-fatty mixture'containing linoleic acid; separating by fractionalcrystallization the tetrahalostearic acid,. which-wasformed by thehalogenation of the linoleic acid-3. from the. other halogene-tedfatty'materials themix-ture; andsubsequently dehalogenatingi thetetrahalo-stearic acid tore-form pure linoleic acid; It is possible torecover pure linoleic acid by such a means because of the fact that thetetrahalo-stearic 'acids ha-ve meltinepoints which are rather sharp andwhich. are separated. from: the. melting: points of theotherhalogena-ted fatty acids byasubstantial number of degrees'oftemperature.

Another illustrationeof the use of zincas a dehalogenating. agent. maybe. found. in the: art of sterol\ chemistrywherein cholesterol andsimilar sterols areemployedto produce the sex hormonesand variousintermediatesuseful in the preparation. at the sex. hormones.Dehalogenation processesrusing: zincfit into f these processes since. inthese processes cholesterol.- and other sterol' compounds are firstcompletely halo-- a split offi the-alkyll -side chain of the sterolcornpound; and after such" oxidationhastakenplace, the oxidizedhalogenated compound which is'obtained is dehalogenated; to form thedesired intermediate or the desired sex hormone. Also in the sterolfield, it is rather common practice to recover stigmasterolfrom themixture of sterols present. in soybean oil by saturating. the doublebonds of the compounds' in suchmixtureof sterols with halogen atoms andthereafter subjecting this halogenated: mixture tofractionalcrystallization- The halogenated stigmasterol may be readilyseparated from the: other sterols; in such mixture. because of thevarying solubilities of these halogenated compounds: The recoveredhalogenated stigmasterol. may then be subjected to dehalogenation withzincto-re-form. the pure stigmasterol.

It is thus seen; that there. are a: number of valuableapplications of.the use of. zinc as-adehalogenatingagentfor halogenated-organiccompounds. Inallcases in the prior art,v as far as We are aware inwhich. zinc in the presence of.. a short chain organic acid is usedas adeha'logenating. agent in such processes, the dehalogenation is.carried-v out by admixing-the halogenated compound with zinc: and theshort: chain organic acid, e. g. acetic acid, in some suitable vessel,preferably in a vessel to which heat is applied. This is particularlytrue in the dehalogenation of themixtures. resulting from the chromicacid oxidation of halogenated cholesterol compounds and similarsterolcom-pounds in processes for the production of sex hormones andintermediates suitable for the production of sex hor- Thus: in an.article published by Wallis and Fernholz, J. A. C. S. 57', 1504-6-(1935),. such a dehalogenation is carried out by admixing the oxidationmixture resulting from the chromic acid oxidation of chol'esteryl.acetate dibromide with acetic acid andpowdered zinc in a. suitablevessel: and heating this reaction mixture at about 100 C. for aperiodiof about. two hours In U. S. Patent No. 2,180,095., whichdiscloses. the production from. cholesterol and similar sterols, such assitosterol and stigmasterol, of intermediates useful. for theproduction. of. sex hormones, a similar dehalogenationprocess isdisclosed.

The prior art. processes. for dehalogenating halogenated compounds with.zinc have. in most cases given very good yields of the desireddehalogenated compounds. importantv exception, however, isin. thedehalogenation of the halogenated compounds. which arepresent. in thereaction mixtures. resulting. from. the chromic acid oxidation ofhalogenated. sterol' compounds. It

sterol nucleus. preventing such splitting or destruction or" the 3 isnot known just exactly why in the latter case the prior art processes donot give as good yields as desired but since the halogenated compoundsare in contact with the zinc for a considerable period of time, it isentirely possible that a number of undesirable side reactions occurduring the dehalogenation process which produce compounds other thanthose desired, thus reducing the a'"- I tual yield to an amount lessthan that theoretically obtainable. This is probably accentuated to aconsiderable degree by the complexity of the mixtures resulting from theoxidation of halogenated sterol compounds. Furthermore the presence insuch oxidized mixtures of many'compounds other than the desired oxidizedhalogenated sterol compounds probably has a detrimental effect upon thedehalogenating agent reducing its efliciency and thus reducing the yieldof the esired dehalogenated compounds. The longer the dehalogenatingagent is in contact with this highly diverse mixture, the greater willbe the reduction in its efficiency. Such an adverse effect would be animportant factor in the prior art processes because of the relativelylong periods of contact between the halogenated compound and thedehalogenating agent in such processes.

It is known, of course, that chromic acid oxide. tion of sterolcompounds produces mixtures of compounds which are of a highly diversenature and which usually contain only small amounts of the desiredcompounds due to the fact that it is not possible to control accuratelythe oxidation of the halogenated compounds so as to produce the desiredoxidized materials. In other words, the oxidation, which is very severe,does not always proceed along the desired lines. ases the halogenatedsterol compounds which In many are being oxidized may be split somewherein the In fact it is for the purpose of sterol nucleus that the sterolcompound is halogenated in the first place since if the double bond orbonds in the sterol nucleus were not protected by some means such ashalogenation thereof,

splitting of the sterol nucleus at the double bond would occur in everycase, thus resulting in a complete failure to produce any of the desiredcompounds.

It is the object of this invention to provide an A improved process fordehalogenating halogen-' ated sterol compounds which have been subjectedto oxidation with chromic acid.

A further object of the invention is to provide a process fordehalogenating halogenated sterol l compounds which have been subjectedto oxidation with chromic acid which will give substantially higheryields and which will be simpler in operation than present processes fordehalogenating such materials.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

It has now been discovered that the above and other objects of theinvention may be accomplished by carrying out the dehalogenation of anoxidized halogenated sterol compound by aproc ess which comprisesdissolving the halogenated compound in a short chain organic acid whichacid, if desired, may be admixed with up to about two and a half volumesof a suitable fat solvent,

Such a dehalogenation process gives much pound than prior art processes;furthermore, the equipment necessary to carry out this process issimpler than that required in the prior art processes and it requiresless operating space than the prior art equipment. The cost or" carryingout the process by this means is less-than in the prior art processessince not only is" the equipment which is used less expensive and lessexpensive "to operate but also by admixing the zinc with a suitableinert material the amount of dehalogenating agent which is required willbe less than that which must be used in order to carry out thedehalogenation in accordance with the prior art methods.

The process of the present inventicnis eminently suitable for use indehalogenating any of the halogenated compounds present in reactionmixtures formed by the chromic acid oxidation of haolgenated sterolcompounds. Thus the process of the invention is quite valuable for usein processes for the production of androsterone, cholenic acid, hydroxycholenic acid, hy droxy norcholenic acid, and hydroxy bisnorcholenicacid and other compounds suitable for use as intermediates in theproduction of sex hormones. It is well known,'of course, that sterolcompounds prior to being oxidized with chromic acid are treated so as toconvert the free hydroxyl group at the 3 position to some group whichwill not be affected by the oxidation reaction, for example, an estergroup or an ether group. For the purposes of the process of ourinvention, it is im' material, of course, how the 3 position of thehalogenated sterol is protected during the oxidation reaction. The mostgeneral practice, however, as is well known, is to form either theacetate or benzoate ester of the sterol, and then to subject thehalogenated product formed from such ester to the oxidation reaction.Also, as far as the process of our invention is concerned, it makeslittle difference as to which particular sterol is used as the initialstarting material as long as it is one from which products are made byoxidizing a halogenated derivative thereof. At the present timecholesterol is the sterol most frequently used as a starting material insuch processes. Sitosterol, stigmasterol and similar sterols are alsoquite useful in producing valuable derivatives by means of suchoxidation reactions. In every case where the dehalogena- -tion of suchoxidized halogenated sterol comcompared to the yields obtained by theprior 'art methods.

The dehalogenation process of our invention is carried out by dissolvingthe oxidized halogenated compound in a solution made up eithercompletely of a short chain organic acid or of a mixture of a shortchain organic acid and a suitable fat solvent. This acidic solution ofthe oxidized halogenated compound is then passed through a column whichis packed with zinc or which is packed with a mixture of zinc and someinert material. The short chain organic acids which we prefer touse inthe process of the invention to dissolve the halogenated compoundsmixtures of these acids.

are acetic acid and propionic acid or suitable If desired, there may beadmixed with such an acid up to about two and a half parts of a suitablefatsolvent for each part of acid. Thus rat solvents such as ethyleth-er,- halogenated hydrocarbons suchas arease methylene chloride,ethylene chloride; ethylene dichloride; etc.-, esters such as methylacetate and-ethyl acetate; ketones such asacetone, etc, may beemployed.The amountof organic'aci'd or mixture of organic acid and-fat solventwhich is-used as the solvent'in relation-to theamount ofhalogenatedcompound-which-is to be dehalogenated may vary, althoughusually it ispreferrednot to employ any more solvent or solvent mixturethan is necessary to -completely dissolve the halogenated compoundwhich-isto be dehalogenated but, if desired, -lar'ger. amounts ofsolvent may be employed. It might be thought that the use ara-halogenated fat solvent inithe process would result in dehalogenationof'such fatsolvent and thus interferew ith the dehalogen-anon of the'compound 'which itilis'desired to dehalo'genate} however, the:halogenated fat solvents which are employed' contain" their: halogenatoms in a much stronger chemically bound condition than the halogen inthe halogenated compounds which it is desired to dehalogenate andtherefore no detrimental results are obtained by the-useof suchsolvents.

The'column which is employed in the dehalogenationprocess-ispacked withzincmetal or a mixture of zinc metal and some inert material such assiliconcarbide (sold under the trademark of Sarborundum), glassor othersuitable-inert packing materials. It hasbeen found that such inertmaterial may be admixed with the zinc metal in-l1flt0-a5 muchas-equ'alparts ofinert material per each-part of zinc without detrimentallyaffecting the results which are obtained. In fact, it is preferred toemploy at least one part oi such an inert packing material for each'twoparts of zinc since we have found that higher yields of the desireddehalogenated compounds are obtained when this is done as compared towhen thecolumn is packed entirely with zinc. The'exactreasons for suchhigher yieldshave not been determined but We have found that such isactually'the case. It may be that the'inert" material aids in keeping,the packing in the column in a porous condition thus insuring a rapidflow of the solution of the halogenatedcompound through the column.Furthermore; we have also found that by packing the column withsuch'ine'rt material the amount of zinc which is used up 'inthe'processl is considerably decreased witha' decrease, of course, inthe cost of the process.

The amount of zinc which is placed in thedehalogenation columnwillusually be somewhat greater than the amount ordinarily employed in thezinc in the column we have found that con sumption of the'zinc by theprocess is considerably: iess' than in the priorart dehalogenationprocesses. hen an inert material is admixed with the zinc in thedehalogenation column, the

amount of zinc plus inert material will be the.

same as when the column is packed completely with the zinc.- In eachcase, the total amount of packing in the column should on the-average befrom about twice to above five times the amount of zinc whichis-=theoretically -necessary.

to completely dehalogenatethe halogenated ma;- terials' which are to be:deh'alo'genated' in the column. When an inert materiaL is= admired withthe zinc, it is' necessary-of course, to have an amount of zinc'in thecol'umn whichwill be sutfi'cient to accomplish the desireddehaloaen'aion. There is nodisadvantage in usin'ganexce'ss-amountofpacking material in the column since in every case the acking material,after being washed toremove materials such as com pounds produced' bythe reaction of theorganic acid with the zinc, e. g. zinc acetate, etc.,may be reused in alater dehalogenation. Therefore, in most cases,v itis. preferred to use an excess amount of packing; in the column overwhat would theoretically be required to complete the dehalogenation.

The diameter and lengthof'the dehalogenation column may varyconsiderably and likewise the shape or the column may be' variedconsiderably. As a matter of convenience iti is preferred to employ.acylinder ofeiher'glassor some material such as steel and to pack suchcylinder with the d'ehalogenat'ing. agent. The diameter orcrosss-sectional area of, the column may be varied and ordinarily itwill be governed by the size of the batch which is being passed throughthe column. Thus, inlaboratory operations, a column havinga diameter'ofonly llor ,2 inches is suitable whereas-in plant operation itispreferred to employ a column having a diameter of at least 5 or 6inches. Likewise, the length of the column may vary andordinarily; itwill depend somewhat upon the'diameter ofthe column inasmuchas'itisdesirable to have the solution of the halogenated compound pass over arelatively large surface area of the-dehalogenating: agent. Thus if acolumn is employed which has a relatively large cross-sectional-area,the height of the column may be substantially less than the height of acolumn having only a relatively small cross-sectional area.

In passingthe solution of thehalogenated organic' compounds through thedehalogenation column, the solution is preferably passed through thecolumn by gravity flow as a matter of convenience. Thus the solution maybe placed in a suitable vessel located above the top ofthe column andthe solution then slowly added tothe column at th top of the column. andallowed to flow rapidly through the column" and as it comes out thelower end of the column'it is collected in a suitable vessel. Ifdesired, however, the solution may be added to the column at-the bottomthereof: and then forced upwardly by pressure flow and the solution ofthe dehalogenated organic compound collected from the top of thedehalogenating column. Also, if desired, the column maybe placed inahorizontal'position or in any position between a horizontal and avertical position and the solution ofithe halogenated compound thenpassed therethrough from either end of thecolumnr In such a case,particularly if the column is in 'a substantially horizontal position,

7 it may be desirable to provide meansfor slowly rotating the column soas to insure'proper contact of the halogenated organic compound with thedehalogenating-agent. In all cases the rate of fiow of thesolutionthrough the columnshould be at ieast'approximately equal to the rate atwhich the solution will now through the column because ofithe force ofgravity when: the column is-in a verticalposition-and thesolutionisintroduced into the column at I the top: thereof;

By employing columns of considerablelcrosssectional area and relativelylong length, it is possible to carry out a substantially continuousdehalogenation process. In most cases, however, it is preferred to run afairly large amount of a solution of the compound to be dehalogenatedthrough the column and then subject the dehalogenating agent in thecolumn to a treatment which will remove therefrom materials which is atleast 20 mesh in size and preferably zinc of about mesh in size isutilized; however, larger or smaller sizes of zinc may be used ifdesired. It is usually desirable to employ as an inert material somematerial which is of a size slightly larger than the size of the zinc inthe column so that, if desired, the zinc may later be readily separatedfrom th inert material by a simple screening operation. Thus in thepreferred packing which w employ, We utilize 10 mesh zinc and 8 meshsilicon carbide. After a dehalogenation reaction has been carried out inthe column, the packing material may be removed therefrom and the zincrecovered by a simple screening of the packing material. Thereafter, ofcourse, the

recovered zinc may, if desired, be admixed again in the properproportions with an inert packing material and used for anotherdehalogenation reaction. It is sometimes desirable to separate the zincfrom the inert packing material following a dehalogenation reaction inorder that the amount of zinc which was used up in the reaction may bedetermined and in order that if such zinc is to be reused it may bereadmixed in the proper proportions with an inert packing material.

For a fuller understanding of the nature and objects of the invention,reference may be had to the following examples which are given merely asfurther illustrations of the invention and are not to be construed in alimiting sense.

Example I A dehalogenation column was prepared by packing a glass tube,which was 90 cm. in length Two liters of an acetic acid-ethylendichloride solution of the product resulting from the chromic acidoxidation of cholesteryl acetate dibromide were placed in the droppingfunnel. The funnel was then opened suiiiciently so that it required 4hours for the two liters of solution to enter the column. At the sametime that this dehalogenation was being carried out in the column,

= another two liter sample of the same solvent solution of the productresulting from the chromic acid oxidation of cholesteryl acetatedibromide was subjected to dehalogenation in accordance with th priorart processes wherein the two liters of the solution were placed in alarge flask and stirred for 2 hours at 45-50 C. with 33 gms.

- of zinc dust.

Both solutions after the debromination was complete were poured intowater and the aqueous mixtures obtained were extracted with ethylenedichloride. The ethylene dichloride solutions which were obtained weresubjected to distillation and the residues remaining after suchdistillations were dissolved in methanol, chilled to crystallize anycholesteryl acetate therein and then filtered to remove suchcrystallized cholesteryl actate. Each methanol solution was then treatedwith semicarbazide hydrochloride and pyridine to precipitate thesemicarbazone of dehydroisoandrosterone acetate. The sample which wasdehalogenated in accordance with the prior art processes gave 1.92 gms.of semicarbazone whereas the sample which was dehalogenated by theprocess of the present invention gave a yield of 2.21 gms. ofsemicarbazone which was a 15.1% higher yield than the yield obtained bythe prior art processes.

Example II A dehalogenation column was prepared similarly as in ExampleI except that in this case the packing used consisted of 800 gms. of 10mesh zinc and 800 gms. of 8 mesh silicon carbide. The glass tube whichwas used for the column had a length of 98 cms. and a diameter of 1.0cms. 8.3% liters of acetic acid-ethylene dichloride solution of theproduct resulting from the chromic acid oxidation of cholesteryl acetatedibromide were introduced into this column over a period of 6 hours andat the same time a 9 liter sample of the same solution of the oxidationproduct was debrominated by the prior art process explained in ExampleI. The dehalogenated material in each case was worked up in the samemanner as in Example I giving a yield of 11.91 gins. of semicarbazonefrom the process of the invention and a yield of 9.48 gms. ofsemicarbazone from the prior art process (the latter figure has beenadjusted for the difference in starting volume). Thus there was a 25.6%greater yield with the process of the invention as compared to the yieldof the prior art process.

Example III Similar comparative runs were made in this example as inExample II using a column the same as that in Example II, but using adifferent batch of oxidation product. In this case the process of theinvention gave a yield which was 31.5% higher than the yield of theprior art process.

Example IV 8.5 liters of an acetic acid-ethylene dichloride solution ofthe product resulting from the chromic acid oxidation of cholesterylacetate dibromide was diluted with 20 liters of water and then extractedfive successive times with ethylene dichloride using 2 liter, 1 literand then 3 diiferent 500 ml. portions of ethylene dichloride. Thecombined ethylene dichloride extracts were concentrated to 2.84 litersby distillation under reduced pressure and in the presence of 50 gms. ofpotassium acetate. One liter of acetic acid was admixed with the 2.84liters of the ethylene dichloride solution and the resulting solutionthen passed through a glass column 84 cms. in length and 2.5 cms. indiameter which was packed with 300 gms. of 10 mesh zinc and 300 gms. of8 mesh silicon carbide. The rate of flow of the solution into the columnwas adjusted so that a period of 6 hours was required to introduce allof the solution into the column.

At .the *same atime an :equal sized :aliquot of'i'the same Oxidation.product was debrominated in accordance with the :prior .art process.The process of the present inventiongave a yield of 11:43 .gms. -'of:semicarbazone whereas the prior art process .gave aryield of 9.82'gms.Thus the process of the {present invention gave a 16.4% higher Tfiildthan thexprocess .of the prior art.

Example JV nnother'dehalogenation was carried out using the columnemployed in Example I with the exception that in this casethe'columnwas-packed with 113 gms. of Ill-mesh zinc mixed with Fenske(glass) packing'in alternate zones about 30 mm. deep. The rate ofintroduction of the solution into the column was 1 hour-and 25 minutesfor 2 liters of the acid solution of the oxidized halogenated product.At the same time that this dehalogenation was being carried out, analiquot of the same solution Was being dehalogenated by the prior artprocess. In this case the process of the present invention gave a yieldof 1.54 gms. of semicarbazone whereas the prior art process gave a yieldof only 1.41 gms. Thus the process of the invention gave a yield whichwas 9.2% higher than the yield obtained with the prior art process.

It is evident from the above description and examples that the processof the present inbelieved in the prior art to be necessary to heat thereaction mixture and to employ means of continuously mixing the zincwith the material to be dehalogenated, it is obvious that the apparatusand operating space required in the prior art take up more space andinvolve more expense than is the case in the process of the presentinvention. Furthermore, the process of the invention is much simplerthan the processes of the prior art since it may be carried out bymerely allowing the acid solution of the material which is to bedehalogenated to flow through a column packed with zinc. As has beenpointed out above, it is possible to cut down considerably on the amountof zinc which is required by admixing with the zinc a relatively largeamount of inert material such as silicon carbide, glass or othersuitable inert material. Thus it is evident that the process of ourinvention, although it may seem to 'be a rather simple change from theprior art teachings, is actually a great ad- Vance in the art ofdehalogenating oxidized halogenated sterol compounds. Although the timerequired to dehalogenate a large quantity of a halogenated compound isjust as great when our new process is used as when the prior art methodsare employed, the length of time during which each molecule ofhalogenated compound and dehalogen-ated compound produced therefrom isin contact with a dehalogenating agent is far less when our new processis used than when the prior art methods are employed. This much shortertime of contact of the individual molecules with the dehalogenatingagent is possibly one of the reasons why our process gives so muchhigher yields than the prior art processes since a shorter contact timeundoubtedly reduces the amount of undesirable side reactions whichoccur.

Having described our invention what we claim as new and desire tosecureby Letters Patent is:

3.1. In a process. for dehalogenating' a halogenated sterol compoundwhich has been subjected :to oxidation wherein the dehalogenation of theoxidized halogenated sterol compound is accomplished by reacting theoxidized halogenatedsterol'compound withzincsin the presence of a short"chain fatty acid, the improvement which comprises slowly introducing anacid solution comprising .the oxidized halogenated sterol compound andashort chain fatty acid into a column packed :with .a packing materialselected from the group consisting of zinc and mixtures oflzin'c andinertmateriallin which the inert materialmaycompriseup to aboutr% of themixture, passing theacid solution which has been introduced into othe.column through the column at a rate which is at least approximatelyequal:to the rate at which the solution will flow through the columnbecause of the force of gravity when the column is in a verticalposition and the solution is introduced into the column at the topthereof, and recovering the desired deh-alogenated sterol compound fromthe acid solution after the acid solution has passed through the packedcolumn.

2. The process of claim 1 wherein the acid solution of the oxidizedhalogenated sterol compound contains up to about five parts of an inertorganic fat solvent for each two parts of short chain fatty acid.

3. The process of claim 1 wherein the short chain fatty acid which isemployed is acetic acid.

4. The process of claim 1 wherein the packing material in the column isa mixture of zinc and silicon carbide.

5. The process of claim 1 wherein the acid solution of the oxidizedhalogenated sterol compound contains up to about five parts of ethylenedichloride for each two parts of short chain fatty acid.

6. The process of claim 1 wherein the acid solution of the oxidizedhalogenated sterol compound contains un to about five parts of ethylenedichloride for each two parts of short chain fatty acid and wherein theshort chain fatty acid is acetic acid.

7. The process of claim 1 wherein the acid solution of the oxidizedhalogenated sterol compound contains up to about five parts of ethylenedichloride for each two parts of short chain fatty acid, wherein theshort chain fatty acid is acetic acid, and wherein the packing materialin the column is a mixture of zinc and silicon carbide.

8. In a process for dehalogenating oxidized halogenated derivatives ofcholesterol obtained by the chromic acid oxidation of a halogenatedcholesterol compound wherein the dehalogenation is accomplished byreacting the oxidized halogenated compounds with zinc in the presence ofa short chain fatty acid, the improvement which comprises slowlyintroducing an acid solution comprising the oxidized halogenatedderivative and a short chain fatty acid into a column packed with apacking material selected from the group consisting of zinc and mixturesof zinc and inert material in which the inert material may comprise upto about 50% of the mixture, passing the acid solution which has beenintroduced into the column through the column at a rate which is atleast approximately equal to the rate at which the solution will flowthrough the column because of the force of gravity when the column is ina vertical position and the solution is introduced into the column atthe top thereof,

, and recovering the desired dehalogenated sterol compound from the acidsolution after the acid solution has passed through the packed column.

9. The process of claim 8 wherein the packing material in the column isa mixture of zinc and silicon carbide.

10. The process of claim 8 wherein the short chain fatty acid which isemployed is acetic acid.

11. The process of claim 8 wherein the acid solution of the oxidizedhalogenated sterol compound contains up to about five parts of an inertorganic fat solvent for each two parts of short chain fatty acid.

12. The process of claim 8 wherein the acid solution of the oxidizedhalogenated sterol compound contains up to about five parts of ethylenedichloride for each two parts of short chain fatty acid.

12 13. The process of claim 8 wherein the acid solution of the oxidizedhalogenated sterol compound contains up to about five parts of ethylenedichloride for each two parts of short chain fatty acid and wherein thepacking material in the column is a mixture of zinc and silicon carbide;14. The process of claim 8 wherein the acid solution of the oxidizedhalogenated sterol compound contains up to about five parts of ethylenedichloride for each two parts of short chain fatty acid, wherein theshort chain fatty acid is acetic acid, and wherein the packing materialin the column is a mixture of zinc and silicon carbide.

ROLAND KAPP. RICHARD GRIFFITH.

No references cited.

1. IN A PROCESS FOR DEHALOGENATING A HALOGENATED STEROL COMPOUND WHICHHAS BEEN SUBJECTED TO OXIDATION WHEREIN THE DEHALOGENATION OF THEOXIDIZED HALOGENATED STEROL COMPOUND IS ACCOMPLISHED BY REACTING THEOXIDIZED HALOGENATED STEROL COMPOUND WITH ZINC IN THE PRESENCE OF ASHORT CLAIM FATTY ACID, THE IMPROVEMENT WHICH COMPRISES SLOWLYINTRODUCING AN ACID SOLUTION COMPRISING THE OXIDIZED HALOGENATED STEROLCOMPOUND AND A SHORT CHAIN FATTY ACID INTO A COLUMN PACKED WITH APACKING MATERIAL SELECTED FROM THE GROUP CONSISTING OF ZINC AND MIXTURESOF ZINC AND INERT MATERIAL IN WHICH THE INERT MATERIAL MA COMPRISE UP TOABOUT 50% OF THE MIXTURE, PASSING THE ACID SOLUTION WHICH HAS BEENINTRODUCED INTO THE COLUMN THROUGH THE COLUMN AT A RATE WHICH IS ATLEAST APPROXIMATELY EQUAL TO THE RATE AT WHICH THE SOLUTION WILL FLOWTHROUGH THE COLUMN BECAUSE OF THE FORCE OF GRAVITY WHEN THE COLUMN IS INA VERTICAL POSITION AND THE SOLUTION IS INTRODUCED INTO THE COLUMN ATTHE TOP THEREOF, AND RECOVERING THE DESIRED DEHALOGENATED STEROLCOMPOUND FROM THE ACID SOLUTION AFTER THE ACID SOLUTION HAS PASSEDTHROUGH THE PACKED COLUMN.